Re: skillers and stuff?
I think that the combat skillers will probably boost your damage higher, but the bonuses gained from masteries (frw, resists, weapon mastery) are also quite nice. Although there are the diminishing returns still. I would go for bcombats unless you need some extra res.
For ubers, CoH is definitely your way to go, for obvious reasons - resists (mephisto's conviction WILL hurt) and the extra damage to demons. You will not loose that much damage, but you will be on the safe side.